Not applicable
1. Field of Invention
The CARDIOST relates to a unit capable of informing a user with no medical background when he/she is suffering an Acute Myocardial Infarction in the first 4 to 6 hours of chest pain.
2. Description of Prior Art
There are many electrocardiographic (ECG) measuring apparatuses. Many of them can measure the ST segment (and other parts of the electrocardiogram wave) but are not meant to alert as to the possibility of an Acute Myocardial Infarction, and they have to be used by qualified medical personnel.
The portable electrocardiographic monitoring devices are used for long-term collection of ST segment data and many other measurements. Some of these devices perform simple real-time analyses limited to ischemia period detection and recording. These devices are used over a long period of time (usually 24 hour periods) for passive recording and analysis. After this period the data has to be downloaded from the device and analyzed by qualified medical personnel for the final opinion. These devices have to be carried by the patient for the complete period of data recording, which makes them uncomfortable no matter how small they are.
U.S. Pat. No. 5,433,209 issued to Gallant et al. July 1995 fully describes an ambulatory recording device that measures the ST segment for further analysis by a physician, which is incorporated herein as reference entitled xe2x80x9crecorder unit for ambulatory ECG monitoring systemxe2x80x9d. This unit does not measure the ST segment in immediate analysis and therefore is not able to diagnose Acute Myocardial Infarction in real time at the moment of real pain when it is necessary for the patient to seek medical advice for early thrombolysis. This Patent is intended to analyze all the waves of the electrocardiogram other than the ST segment and the baseline. The mentioned Patent also includes accumulation and recording of xe2x80x9cminute-by-minutexe2x80x9d, xe2x80x9chour-by hourxe2x80x9d and xe2x80x9cend of periodxe2x80x9d summary information that is not used in acute settings.
U.S. Pat. No. 5,713,367 issued to Arnold et al. February 1998 for measuring and assessing cardiac electrical stability and the alternans pattern of cycle-to cycle variability in physiologic waveforms does not measure S-T segment but alternans of the QRS wave to asses the risk of ventricular arrhythmias, as does the signal average electrocardiogram by averaging many repetitive waveforms, and much of the existing hardware can be used for both systems. Neither of these systems is intended for acute ischemia diagnosis.
U.S. Pat. No. 5,584,868 issued to Salo et al. December 1996 is a cardiac stimulating apparatus and method for heart failure therapy that includes a dual chamber pacemaker on an invasive basis that is not intended with our invention, and a cardiac defibrillator for reducing cardiac lethal arrythmia and sudden death by the means of electric shock provided by the defibrillator.
U.S. Pat. No. 3,868,567 issued to Ekstrom et al. February 1975 is related to the PQ level of the same waveform employing delta modulation and demodulation for processing information overlapping the ST segment with a predetermined electrocardiographic form and making an average between two segments of waveforms, but does not trigger any visual or audible alarm intended for early diagnosis of Acute Myocardial Infarction.
U.S. Pat. No. 3,991,747 issued to Stanly et al. November 1976 is a electrocardiographic device for telephonic or radio transmission to an analyzing facility, converting the signs to audio output, not intended to be analyzed by the patient himself, and displays the full extent of the 12 EKG leads. The device described in this Patent does not have an audio or visual alarm.
U.S. Pat. No. 4,318,412 issued to Stanly et al. March 1982 is intended to provide and optimize the placement of cardiac electrodes and to improve the signal processing but is not intended for early diagnosis of Acute Myocardial Infarction nor does it examine the ST segment. This arrangement obtains 90% of the information from a 12-lead electrocardiogram.
U.S. Pat. No. 4,546,776 issued to Bellin et al. October 1985, which analyzes PQ and ST portions of an electrocardiogram waveform and establishes a normal or standard ST ratio deviation between the difference of ST and PQ level, has an actuating alarm if heartbeats exceeds or is lower than a predetermined rate. When the ST segment triggers the alarm it is made on the basis of a standard ST deviation value in this Patent. Also it is emphasized that the ST segment is measured continuously. This invention is intended to be used in exercise conditions such as jogging. While this Patent indicates that a depression of approximately 100 microvolts is usually xe2x80x9cnormalxe2x80x9d, we consider that this degree of depression in acute pain is enough to trigger an alarm of xe2x80x9cmedium riskxe2x80x9d (yellow light). In this Patent the alarm is intended in part to warn the user to xe2x80x9ccease vigorous activityxe2x80x9d and does not seek an immediate use of thrombolisys. The PQ level is used and compared to the ST level instead of comparing to the baseline, which is universal in the electronic signal of any electrocardiogram.
U.S. Pat. No. 4,679,144 issued to Cox et al July 1987 includes a programmable apparatus carried by an ambulatory patient for performing continuous real time analysis of EKG information by permanently carrying the device and analyzing the TP segment against the ST segment. Emphasis is made on the slope of the current EKG amplitude minus previous EKG amplitude, so only the patient intended to use the apparatus can take advantage of the diagnosis instead of any other person where the baseline is used as reference.
U.S. Pat. No. 4,930,075 issued to Kortas et al. May 1990 focuses only on the quantification of the ST depression, slope and length of the ST segment and is a software implemented method for analysis, but is not intended as a device for self diagnosis of acute ischemia. It studies principally a precise mathematical relationship between the values of the S-T segment.
U.S. Pat. No. 4,957,115 issued to Selker et al. September 1990 is intended as a device for determining the probability of death in cardiovascular patients and a method for assessing mortality risk at a health care facility. It is a computer adapted to receive the output and calculate a numerical value representing the output-based probability.
U.S. Pat. No. 5,003,983 issued to Dingwall et al. April 1991 is intended to provide an improved cardiac monitoring system to measure the deviation of the S-T segment and pulse rate in a package that can be easily and unobtrusively attached to a patient, for example, during an exercise routine, or long term monitoring.
U.S. Pat. No. 5,058,597 by Onoda et al. October 1991 has an R wave detector determining the heart rate and the ST value of the ECG signal over a long period of time while being carried by a subject who presses an event switch on feeling a subjective symptom (includes pain) but, instead of triggering an alarm after analyzing the ST segment, the electrocardiographic signal is written to another storage which is assigned to waveforms. The electrocardiograph records a minimum necessary amount of information for screening, i.e. the heart rates, ST values, and waveforms of electrocardiographic signal associated with subjective symptoms.
U.S. Pat. No. 5,181,519 issued to Bible et al. January 1993 detects the ST segment but is not intended to trigger an alarm when any shift of the segment is detected, the associated signal is then stored while the monitoring unit continues to search for further measured ST deviations exceeding the threshold ST deviation and subsequently the recorded signals and associated data can be displayed by transmitting it from the monitoring unit to a remote display unit via a data transmission unit.
U.S. Pat. No. 5,226,424 issued to Bible et al. July 1993 determines the ST segment characteristics useful in diagnosing myocardial ischemia, but operates continuously and focuses on a low energy consumptive portable heart monitor which derives from the fact that processing of the analog data requires considerably less energy than does processing the digital data continuously in normal operating mode and is not intended to trigger an alarm when Acute Myocardial Infarction occurs.
U.S. Pat. No. 5,456,261 issued to Lucky et al. October 1995 analyzes a plurality of the electrocardiographic signals for determining the existence of rhythm abnormalities, infarction, hypertrophy and repolarization abnormalities, and is not a solution for early and immediate diagnosis of acute ischemia and infarction self made by the patient himself.
U.S. Pat. No. 5,464,020 issued to Lerner et al. November 1995 is intended for the diagnosis of subacute cardiac dysfunction and not for acute ischemia.
U.S. Pat. No. 5,718,233 issued to Selker et al. February 1998 is only for continuous monitoring in a patient who has a cardiovascular disease and is a predictive instrument for computing a patient""s probability of a serious cardiac condition, it is not intended to be used in acute settings and pain.
U.S. Pat. No. 5,792,066 issued to Kwong et al. August 1998 is intended to be used in patients who have underlying heart conditions which mimic Acute Myocardial Infarction, and remedies a deficiency in the prior art methods and systems for this diagnosis by detecting a wave amplitude ratio (e.g. the ST complex amplitude divided by the S wave component amplitude at some specified instant in time). It calculates and compares to predetermined criteria and on the basis of this comparison it indicates whether Acute Myocardial Infarction is occurring. Thus it is unique in diagnosis only for the patient who uses the device but cannot be used by any other person if pain is present because it compares ST amplitude divided by S wave component of the same patient against a predetermined criteria rather than against the baseline which is universal for any electrocardiogram, and does not provide any audible or visual alarm triggered by the ST segment shift.
U.S. Pat. No. 5,813,979 issued to Wolfer et al. September 1998 describes storable conductors for expeditiously facilitating the manual administration, storage and dispensing of individual electrode leads to a patient in emergency situations when setup and operation is difficult, and is not intended for self-diagnosis of Acute Myocardial Infarction by the patient in acute pain.
U.S. Pat. No. 5,876,351 issued to Rohde et al. March 1999, in which a medical component is removable and connected to the platform has specialized circuitry specific to a predetermined medical function. It is used for obtaining ECG in a cost-effectiveness basis designed primarily for playing video games.
U.S. Pat. No. 5,562,711 issued to Yerich et. al. October 1996 is provided with circuitry for sensing a plurality of physiologic parameters intended to be indicative of increased cardiac output and is a body implantable cardiac pacemaker.
U.S. Pat. No. 5,662,688 issued to Haefner et al. September 1997 is a system and method that automatically controls a gain of a cardioverter/defibrillator and delivers shock pulses in response thereto. A detection circuit detects depolarizations and provides a signal representing a cardiac event indicative only on depolarization.
U.S. Pat. No. 5,683,444 issued to Huntley et al. November 1977 is an implantable assembly for defibrillation in the form of flexible electrode that delivers energy more efficiently to body tissues than conventional defibrillation electrodes.
U.S. Pat. No. 5,462,504 issued to Trulaske et al. October 1995 is a method and apparatus for maintaining the heart rate of a user of a fitness apparatus and is intended to be incorporated into a treadmill.
U.S. Pat. No. 4,073,011 issued to Cherry et al. February 1978 is an electrocardiographic computer with a multi-speed magnetic tape scanning device for processing and observing in a relatively short interval of time large quantities of ECG signals from two pairs of ECG leads.
U.S. Pat. No. 4,006,737 issued to Cherry February 1977 is a device for processing and observing in a relatively short interval of time large quantities of ECG signals from two pair of ECG leads. The trend information is heart rate and ST segment level to provide a scanning of an entire 24 hour tape in 12 minutes.
U.S. Pat. No. 4,299,233 issued to Lamelson November 1981 is a device on which a human body may lie or recline for body vibrations such as heart pulses, respiration or body tremors. A transducer is operatively coupled to the liquid.
U.S. Pat. No. 4,362,164 issued to Little et al. December 1982 is a audio transducer that has a body which on one side mounts an electrode carrying chest belt. A microphone and a rotor assembly are mounted in a cavity in the body, and communicates through passages in the rotor assembly with the electrode carrying chest bell when the rotor assembly is in a first position and with the conventional chest bell when the rotor assembly is rotated to a second position.
U.S. Pat. No. 4,628,939 issued to Little et al. December 1986 is a method and associated means for producing simultaneous electrical representations of the electrical and acoustic activity of the heart in which a pickup device and associated circuits produce a full wave rectified symmetrical heart sound signal annotated by pulses developed from the QRS wave of the electrocardiogram signal.
U.S. Pat. No. 4,838,275 issued to Lee June 1989 is an apparatus that includes special furniture on which the patent lies an sits, and embedded in which are devices that automatically sense multiple parameters related to the patient""s health. The patient cooperates only passively and transmits these signals from the patient""s home to a central surveillance and control office.
U.S. Pat. No. 5,042,497 issued to Shapland August 1991 is a system for predicting and preventing cardiac arrhythmia for the use in combination with an implanted arrhythmia treatment device. The preventative actions include overdrive pacing of the heart.
U.S. Pat. No. 5,135,004 issued to Adams et al. August 1992 is an implantable device that assists in the diagnosis of myocardial ischemia of a human heart and includes a plurality of electrodes and a like plurality of sense amplifiers for generating an electrogram for each of the electrodes. A digital to analog converter reads the voltage magnitudes of the electrocardiogram ST segments which are then stored in a memory. An implantable receiver,transmitter is arranged to transmit the magnitudes of the electrocardiogram ST segments to a nonimplanted external receiver.
U.S. Pat. No. 5,181,519 issued to Bible January 1993 is a portable apparatus and method for monitoring heart muscle electrical activity includes a plurality of electrical contacts that transmits the signals to the monitoring unit. Whenever a series of ST segments exhibit an ST deviation from the reference axis which exceeds a predetermined threshold deviation, the monitoring unit records data relating thereto which is used for diagnosis of myocardial ischemia.
U.S. Pat. No. 5,235,976 issued to Spinelli August 1993 is a cardiac rhythm management device in which the rate controlling parameter of a rate adaptive pacemaker is the heart""s total active time used as an indication of hemodinamic instability for triggering a defibrillation.
U.S. Pat. No. 5,685,303 issue to Rollman et al. November 1977 is a belt like strip for recording electrocardiograms insuring proper placement on the patient""s chest or precordium during usage.
Foreigns Patents No GB 2061521A issued to DavisHowell Jenkins May 1981 measures the individual""s susceptibility to cardiovascular disorder with a visual indicator displaying one of a series of indications and enabling answers to be entered. Patent SU 1570-709-A issued to Leca June 1990 is a human""s heart action monitor that measures heart contraction frequency and ST segment shift. U.S. Pat. No. 2,315,064 issued to Burchard March 1973 measures ST fall arrhythmia""s with continuously selectable prematurity index and intervals, tachy- and bradycardias, in continuously adjustable intervals and/or frequency regions. Patent DD 281 957 A5 issued to Krinke August 1990 determines the time occurrence of R-blips, QRS complexes and P-waves and allows a complex description of irregularity as well as formulation. Patent DE 3633-983 A issued to Wasser October 1986 measures variations in voltage characteristics and provides a high degree of freedom movement, different output signals are provided in dependence on the variation rate. Patent 5-64632 (A) issued to Takashi Suzuki March 1993 enables quick finding of calculating conditions ensuring a better ST deviation trend graph. Patent 405176906 (A) issued to Mutsuo Kaneko July 1993 measures a peak value of ST segment at an arbitrary measuring point displaying successively generated ST trend graphs, so that many derived electrocardiogram waveforms can be recognized easily.
The object of the CARDIOST is to provide a device capable of instantaneous electrocardiographic measurement and real-time analysis of the ST segment in order to detect an Acute Myocardial Infarction so that a user can differentiate it from other types of chest pain through code color-audible alarms and seek immediate medical attention before 4-6 hours for proper treatment to be installed. This device can be used by the owner himself or by any other nearby person because it uses as reference for the ST segment shift the baseline of the electrocardiogram which is universal for everyone.
Accordingly, the main objects and advantages of our CARDIOST are that it allows for a real-time diagnosis made by the patient himself at the time of acute pain and thus enables him/her to seek immediate medical attention for precordial pain. Failure to consult immediately is one of the leading causes of mortality and morbidity in Acute Myocardial Infarction (AMI) which in itself is a leading cause of mortality in humans. Not to consult within 4-6 hours of acute pain is one of the major public health problems in the world, as supported by thousands of papers and studies all over the world. Other devices which make automatic diagnoses of Acute Myocardial Infarction need to be read and interpreted by a physician who most of the time is not available when the patient really needs the diagnosis.
Another object of the CARDIOST is to provide a portable apparatus, small in size, of light weight, and with a low power consumption, which can measure electrocardiographic data and analyze same digitally and instantaneously.
It is a further object of our CARDIOST to provide a device that measures either a positive or negative ST segment shift from the baseline, providing the user within seconds of the measurement with a warning of a possible Acute Myocardial Infarction.
It is yet another object of CARDIOST to provide a device capable of instantaneous electrocardiographic measurement that can be used easily by any person, preferably the patient himself, even if such person is under the stress of thinking that he/she is having a heart attack.
Finally, the CARDIOST is designed to help a patient to distinguish between the common symptoms of chest pain and those of Acute Myocardial Infarction, which is usually very confusing and subjective.
These and other purposes of the CARDIOST are achieved by means of the embodiment of a portable electrocardiographic measuring and analyzing unit, preferably a small, low-power electronic unit. The electronic unit consists of an electrocardiographic signal amplifier connected to the patient via a five-lead electric connection, a positive electrode at the rear of the device, and a neutral electrode also at the rear part of the device, both of which make contact with the precordial skin of the patient, and three more electrodes placed in the left armpit, right armpit and lower abdominal wall (hipogastrium). The device then immediately measures the signal.
The signal from the electrocardiographic amplifier is digitized by an ADC (Analog to Digital Converter) unit and recorded for a few seconds by an electronic analysis unit consisting preferably of an electronic microcontroller.
The electronic analysis unit extracts the ST segments of the electrocardiographic signal and measures its elevation or depression in relation to the baseline. The ST segment of a typical healthy heart is a straight line of zero slope on or near a horizontal reference axis; if there is a significant deviation from the reference axis, the heart muscle signal is termed anomalous which is indicative of an unhealthy heart muscle. It is of primary importance for the electrocardiogram not to be analyzed against a predetermined and stored reference or normal value for the patient but against the baseline so it can be used not only by the owner himself of the device and thus it can help body around him to diagnose acute ischemia if needed, considering that the baseline is a universal electronic signal of any human electrocardiogram. Depending on the result of the ST analysis in a few ECG signal periods, the electronic analysis unit turns on an alarm if the analysis indicates the possible presence of an Acute Myocardial Infarction.
There is great public health concern as to an early diagnosis of Acute Myocardial Infarction, given that a large proportion of patients fails to seek medical attention within the first 4 to 6 hours of the onset of chest pain. If proper medical diagnosis and care are provided within this critical period (of the initial 4 to 6 hours), many lives can be saved with the use of thrombolysis drugs or any other treatment that can be furnished upon further investigation. It is for these cases that the CARDIOST is intended.
Further objects and advantages of our invention will become apparent upon consideration of the drawings and ensuing description.